Web conditioning



Nbv. 27, 1962 R. R. WALTON WEB CONDITIONING Filed Dec. 21, 1960 UnitedStates Patent" Onice .3,06I6 64s I II IWEB coNnrr lorqmc Richard R.wanna, 10 w. Hill Place, Boston, Mass. Filed Dec. 21, 1960, Ser. No.77,423 Claims. cl. 117''-111) This invention relates to the uniformmetering of small amounts of moisture into absorbent webs such as paperand knitted, woven and unwoven textiles, includin'g particularlyflattened circularly knitted tubes. Em- Bodirnents of the invention arealso useful for imparting much higherliqnid concentrations to webs.

1 Selected textile and paper Webs can be physically altered by creping,compacting and similar physical operations to' obtain desiredcombinations of web characteristics including compactness, absorbency,elasticity and filt ering power. While the degree of each of the desiredcharacteristics obtained depends on the kind of web selected, and thenature of the particular physical operation, a furtherimportant factoris the condition of the web fibers at the time of the operation. As anexample, if a given paper web has a moisture content in the range of50-100 percent (as compared to the dry weight of the web), while it canbe creped, such may only be achieved at a substantial loss in porosity.On the other hand, creping such a Web at normal ambient moistureconditions, while perhaps improving absorbency and porosity, has nosubstantial effect upon its elasticity and compactmess. This is notsurprising when the conditions of the fibers in such webs areconsidered. At ambient conditions the fibers contain around 5 percentmoisture and are, therefore, quite dry and spring-like, and tend tospring back to their original shape after dry creping; at highmoisturelevels the fibers haye little or no dimensional stability andslight physical forces drastically compress the web structure.

I There are intermediate moisture conditions, for example at aroundpercent total moisture for commercial grades of kraft paper, at whichweb fibers are at a plasticity threshold and can be creped to achievemoderate elasticity and compression of the web structure while thefibers have sufficient strength and resiliency so that desired levels ofweb characteristics such as porosity are obtained. I I I p I I I Whilethese moisture dependent changes in fiber behavior have long beenappreciated, there has been no general commercial use of creping, (5 s.,of absorbent webs with fibers at the threshold of plasticity and atsimilai low moisture levels due to the lack of a suitable method andapparatus for" uniformly and controllably irnparting small amounts ofmoisture to the webs. I

For highly absorbent webs, momentary contact with any source of excessliquid gives an immediate saturation to 100 percent and r'nore, anduniformcontrolled liquid amounts cannot practicably be removedthereafter; For moderately absorbent webs, when an excess of moisture isapplied, and then an attempt is' made to dry or doctor off the liquid,it is generally impracticable to get down to low uniform concentrations.The web characteristics to be obtained by physical altering of such websare undesirablylimited, and many paper webs in these categories havesuch high plasticity and low wet strength that Iran dling of the wetted'webs, if feasible at all; is at least very difficult. v 1

Even for webs having lower absorption rates, operation at the thresholdof plasticity has not been ensured be cause of the inherent inaccuraciesand variabilities in the known methods for imparting moisture. Forexample, due to lack of ameans for uniform moisture metering, a S'afetyfa'ctOr of excess moisture has been necessary to ensure that all thefibers in the web receive at least enough moisture to become plastic.Because of the excess inois: ture, the optimum. of the desiredcharacteristics often cannot be reached: After the creping or otherphysical operation, an extended drying step has been needed to removethe moisture. I I I I I I I A principal objective of this invention is,therefore, to provide a method and apparatus for accurately impart: inguniform controlled small amounts of moistureto absorbent websincludingthose which arevery highly absorbent, and providing forselectably varying the co ncentration of moisture imparted commensuratewiththe type of web involved, the amount of ambient moisture in the web,and the condition of the web desired to be obtained. I I I I.

Water has heretofore been applied to Webs by hard rolls having etched orknurled surfaces in concentrations fixed principally by the degree ofroughness of the roll surface. It is not possible; withou t the effortand expense of substituting one such roll for another, adequate; ly tocontrol the amount of liquid which, can be applied to a web to obtain aselectable range of low concentrations. Due to continued contact withthe web and the nature of the surroundings, fine particles of duS,-,.ab'so'rbent lint and the like become imbedded and buildup in thesurface of such hard surfaced rolls, which disrup'ts accurate controland causes substantial unevenness in the amount of water which iscarried and imparted to the web. Additionally, where such rolls are, forinstance; of steel; traces of oil often occur on the surface whichprevent wetting and disrupt drastically the uniformity with which watercan be carried and imparted by the roll The instant invention eliminatesthese problems. It provides a method and apparatus'whichachievesselectable variation in the amount of water imparted during operationwithout stopping and obviates both the need to have on hand numerousetchedrolls and the work in-i volved in changing them. Additionally, themetering roll of this invention is uniquely self-cleaning, and dust andlint are not a problem. I I I Particular embodiments of the inventioninclude a singleapparatus for imparting saturating amounts of liquid aswell as controlled low concentrations of moisture and an apparatus forconditioning both sides of a relatively thick web such as knitted goods.I

I The invention, while including the important conditioning of webspreliminary tocreping and compacting, .i-s not strictly limited theretoin its broadest aspects. Forinstance, the invention comp-rehends theaccurate rehydra' tion of absorbent webs which have been unduly dried byprevious subjection to heat or vacuum. I

Inthe drawings:

FIG. l is a perspective of a preferred embodiment of the apparatusthr'eaded and adjusted to accurately me: ter low" concentration moistureinto a web; v

FIG: 2 is a somewhat magnified diagrammatic rep' e sentation in plan ofa portion of the metering surface member of FIG. 1;-

FIGS. 3 and 4 are still further magnified plan and sectionaldiagrammatic views, respectively, depicting the metering surface member;I I

FIG. 5 is apartially broken away, diagrammatic sec-H. tional end view ofthe apparatus of FIG. ,.l, exaggeratedis new the effect upon themeteringsurface of selected adj u'stine'iitsthat caus I eont riling andthe imparting e' rolls to engage the metering roll with substantial aportion the ter of nip where pre FIG. 7

meter ing surface member; and

Patented Nov. 27, 1962 I FIG. 8 is an end view of a preferred embodimentparticularly adapted for conditioning knitted and woven textile websthrough both sides.

Referring to FIG. 1, the apparatus comprises a stationary frame 18 uponwhich is rotatably mounted a metering roll 20, driven by chain 23 andprovided with a metering surface member 40 hereafter more fullydescribed. Roll 20 provides a surface shown as steel, suitable forapplying pressure to a resilient metering surface member. Similarly, adense rubber cylinder can be employed.

A controlling roll 22 having a generally smooth surface is freelyrotatably mounted on a support arm 27, and the arm is pivotally securedto frame 18 to carry roll 22 into nip relation at 21 with the meteringroll 20. The pivoted arm 27 together with pneumatic jack 26 provides foradjusting the pressure with which roll 22 engages the metering roll.This jack is adapted to vary accurately the force applied between therolls by controlled variation of pneumatic pressure applied to it, likejacks 36 hereafter described, and similar jacks on the opposite side ofthe apparatus (not shown). A vat 24 mounted on frame 18 below roll 22 isadapted to furnish liquid to the meteringsurface 40 by immersing a lowerportion of roll 22, which upon rotation carries a film of the liquid tometering surface member 40, the surface of the roll 22 being adsorbentto the liquid, e.g., of a smoothly ground dense rubber surface. Thewater may contain slight amounts of additives to improve wetting. Thus,in addition to the prime function of controlling the amount of watercarried by the metering roll to the web, hereafter explained, roll 22cooperates with the vat to provide an initial flooding supply to themetering roll. With the arrangement shown in FIGS. 1 and where themetering roll 20 is engaged by the upper surface of roll 22, excessliquid at the meniscus 54 tends to flow downward, away from the nip,counter to the movement of roll 22. This promotes stable, uniformflooding of the metering roll member 40 over a wide range of operatingconditions, including substantial roll speeds.

An imparting roll 28 is rotatably mounted in a nip relation at 29 withthe metering roll on support arm 37 pivotally secured to the frame. Thenip is adapted to receive a web 32 for conditioning at low moistureconcentration levels. Controllable pneumatic jack 36 secured at one endto the frame and the other to the support arm 37 controls the pressurewith which roll 28 causes engagement of web 32 with the metering roll.The surface of roll 28 can be polished stainless steel (or as will beseen in the embodiment of FIG. 8, according to the invention, for knitgoods it may be another metering roll). This roll serves to vary theratio of amount of liquid imparted to the web to the total amount ofliquid carried from nip 21 by the metering roll.

The metering surface member 40 of metering roll 20, according to theinvention, comprises a multiplicity of adsorbent surface elements havinga limited absorbency, if any, arranged to provide an even distributionof small resiliently deformable capillaries closely arranged throughoutthe outer surface. I have found that a freshly rough ground rubber rollprovides such capillaries, but pressures applied thereto soon causeinoperative glazing of the roll surface. According to the invention,fibers are employed to define the surface elements, together with aresilient material such as rubber which extends at least partiallyaround the fibers in an intimate relation therewith so that thecapillaries are resiliently deformable over a range by pressure appliedto the surface over a corresponding range. While this resilient materialcan be in the form of a coating over the fibers, a substantial resilientmaterial thickness under the surface elements is useful to absorb to aslight degree the nip pressure so that the rangeof resilient deformationof the capillary structure is extended over a somewhat wider range oftotal nip 4 pressures. Where the roll 20 is dense rubber, the backingcan be integral therewith.

The capillaries are limited by the intimate rubber or similar resilientmaterial, providing only a limited capacity for capillary retention ofwater.

According to the invention it is important that there be a great manycapillaries per square inch in the surface, uniformly distributed, foronly by this is the threshold of plasticity in the web fibers or otherdesired low moisture content uniformly reached.

Referring to the diagrammatic plan representation of FIG. 2 and thehighly magnified, diagrammatic views of FIGS. 3 and 4, the surfacemember 40 has a particularly large number of evenly distributed tinycapillaries defined by adsorbent, textile threads comprised ofessentially nonabsorbent fibers 4-2 crossing in a weave, here fifty endsin each weave direction. This is bonded intimately with a rubber backing44 so that the rubber extends into the interstices of the bonded textileunderface, covering that side of the fibers and effectively resilientlysupporting the textile at both the crossings and the valleys. Theresilient character of the woven threads and intimate rubber backingprovides resiliently deformable capillaries, and the intimate resilientmaterial limits the total water retentive capacity of the member. Thisprovides an outer capillary surface which when flooded retains an evendistribution of water. This surface reacts to displace and remove waterwith a predictable and controllable degree with pressure dependentdeformation of the capillaries by the controlled nip towards which thecapillaries move. The textile fibers provide a surface which will wearwell and will not glaze or otherwise lose its water pick-up capacity.

To provide the essentially nonabsorbent character of the capillarystructure, fiber components of my metering surface member where they arenot wholly impermeably coated or impregnated as with rubber, must be ofnonabsorbent composition or, if absorbent, the aggregative absorbency ofthe fibers must be limited. Thus Where a woven textile comprised ofexposed absorbent fibers, the textile weave must be very tight and thethreads thereof highly twisted providing a relatively hard finish, whichcooperates with the intimate impermeable backing to prevent entry oflarge quantities of water into the fibers. I have found that anaggregative absorbency of any substantial degree such as occurs with anexposed surface of knitted or normally woven cotton material isunsuitable as uncontrollably large amounts of moisture are transmittedto highly absorbent rolls, being conditioned even with the use ofextreme nip pressures, and the surface mats down. Hence, it is criticalto my invention as applied to conditioning absorbent 'webs that anymetering surface absorbency must be of a limited character in accordancewith the above.

With reference particularly to FIGS. 1 and 5, the operation of thisinvention is as follows:

A web 32 which may be paper, knitted, woven or unwoven textile or thelike is fed through nip 29. Controlling roll 22 driven by movement ofmetering roll 20 delivers a smooth film of liquid 50 to the metering nip21. This liquid forms a flooding meniscus 54 at the nip, and thecapillaries 40a are fully flooded. The flooded resiliently deformablecapillaries at 4011 are narrowed as they approach the line of centers ofthe two rolls in a predictable amount dependent upon controlled nippressure, and excess water is forced from the capillaries back into themeniscus. Referring to FIG. 6, controlled small evenly distributedamounts of water are carried by the narrowed capillaries representeddiagrammatically at 46 to the line of centers and beyond. Similarly, theamount of pressure of the web 32 against the metering roll 22 exerted byroll 28 predictably deforms the capillaries and the web fibers contactthe water in the capillaries as the capillaries are deformed. As theultimate size of each tiny capillary in the metering surface availableintimately bonded to each textile layer. 54 is bonded to themeteringroll 20. The resilient rubber the textile as shown diagrammatically at58. rubber coating seals the textile fibers from the water, the

for carrying liquid is defined by the amount of pressure applied to themetering surface, the concentration of liquidleft in the meteringsurface member and-the conpressure exerted by roll 28 determines to finedegree the ratio of liquid imparted to the web to that remaining in thecapillaries as they move away from web contact.

Referring to FIG. 7, a preferred metering roll surface member 50comprises a rubberizedsandwich of two textile layers 52, 54 in 'which aresilient rubber core 56 is Textile layer backing 56 while performingsimilarly to backing 44 of FIG. 4, also extends over the outer surfacein the form of a coating which conforms in detail to the pattern of Asthe great number of fibers in the woven textile themselves can beabsorbent because the capillaries are wholly rubber lined so thatresiliency is assured.

The repeated resilient deformation and return'of these metering surfacesin addition to the controlled meter ing metering feature serves afurther important function. The

metering surface is often exposed to lint and dust, which i if allowedto remain, would obstruct the control and would adversely affect theevenness of distribution of liquid to the web. But lint and dustparticles cannot accumulate here because, due to the continued flexingof I the metering surface, they are not allowed to reside. Particles areurged outwards by the pressure deformations pacted or creped productwill be systematically observed, and should there be an indication thatthe condition of plasticity of the web is not quite right, appropr-iateadjustments of the pneumatic jacks or similar pressure controllers willbe made.

The apparatus of the embodiment of FIG. 1 is also adapted to imparthigher concentrations of liquids to substrates. The nip 21 between therolls and 22 of the embodiment of FIG. 1 is accessible from both sides,Ipermitting a substrate to be threaded therethrough, whereby virtuallythe entire film of liquid picked up by roll 2'2 can be imparted to thesubstrate.

Also, an idler 70* is positioned in the liquid supply vat 24, spacedapart from roll 22, and a substrate can be led over this idler, throughthe liquid under roll 22 and out again, whereby both sides of thesubstrate are exposed to the liquid in the vat.

Referring to the embodiment of FIG. 8, accurately controlled, lowconcentrations of moisture are applied to both sides of a knittedtextile web 68 which can be a double thickness, flattened circularly,knitted tube or the like by two opposed, "relatively adjustable meteringsystems wherein the surface of each of opposed metering rolls 7% and 72operate similarly to metering surface member heretofore described, andeach also serves as an imparting pressure roll to the other, cooperatingto promote fine control of liquid application, controlled by therelative positioning of the two.

It will be understood that the range of low concentrations of liquidmetered onto substrates can be varied by heating the liquid and byadding chemical wetting agents. The metering surface can be flooded bydirect spraying or immersion preceding the contact with the controllingsurface in an embodiment employing certain of the teachings of theinvention.

A variety of liquid solutions and suspensions 'canbe controllably anduniformly applied to webs with *the moisture metering'apparatusincludingfor instance liquids containing clays, starches and resins.

It is sometimes helpful to apply steam to a web preliminary to moisturemetering (e.g., to facilitatespreading of knitted goods) and to applysteam after metering.

A web can be passed through a nip of squeeze rolls after metering forWorking liquid into web structure.

Numerous of the particular details of the invention can be modifiedwithin its spirit and scope.

What is claimed is:

l. A moisture metering apparatus comprising a continuous meteringsurface member of resilient and fluid adsorptive material of 'no morethan limited'aggregative absorbency having a multiplicity of evenlydistributed outwardly disposed resiliently deformablecapillariesgenerally defined by "evenly distributed fibers disposedthroughout the surface thereof, and'an intimate resilient nona'osorbentmaterialengaging at least partially'around the fibers in an intimaterelation therewith, said metering surface member being mounted formovement with a hard pressure exerting member through a web contact zoneat which a web'can be trained againstsaidrneterin'g surface member toimpart moisture thereto, a'wat er supply for furnishing water to aflooding Zone apart from said web contact zone for flooding saidmetering surface member, a controlling surfacemember disposedbetweensaid flooding Zone and said web contact zone transverse to the directionof movement of said metering surface member and engaged thereupon forcompressing said member against the pressure exerting member moving withsaid web, and adjustment means adapted foreontrolled variation of thepressure exerted by said controlling surface member uponsaidmetering'sufface member to control the amount of water carried by thelatter to said Web contact zone.

2. The moisture metering'apparatus of claim 1 wherein said fibers arecoated generally throughout with readsorbent surface member mounted formoving contact with said metering surface member, and said water supplyis adapted to provide water to said controlling surface member wherebywater thus applied is carried to and floods said metering surfacemember.

6. The moisture metering apparatus of claim 1 wherein an adjustableimparting pressure means is-disposed at said 'web contact zone, adaptedto'controllably valry the pressure of contact of said web against saidmetering surface member. p

7. The apparatus of claim 6 wherein said adjustable impart-ing pressuremeans comprises a hard continuous surface member adapted for movingengagement with said web at said Web contact zone, and an adjustmentmeans for controlled variation of the pressure between said meteringsurface member and said continuous surfaced member to vary pressure ofengagement against said metering surface of the web to controllably varythe concentration of moisture imparted to said Web.

8. The apparatus of claim 7 wherein said continuous surface membercomprises a second metering surface member adapted to be provided with acontrolled amount of fluid, whereby low concentrations of moisture canbe applied to opposite surfaces of a web simultaneously.

9. A moisture meter-ing apparatus comprising a rotatably mountedhorizontal metering roll, a rotatably mounted controlling roll in niprelation therewith, means for adjusting the relative pressure betweensaid metering roll and said controlling roll, and liquid supply meansfor furnishing liquid to flood the surface of said metering roll withliquid preceding pressure contact of said metering roll with saidcontrolling roll, said metering roll having an outer cylindricaladsorbent surface of no more than limited aggregative absorbencycomprised of a large number of evenly distributed outwardly disposedresiliently deformable capillaries, defined by closely disposed fibersprovided with resilient, nonabsorbent material in intimate relationtherewith and said metering roll having a hard inner body ofsubstantially the same diameter as said outer surface, said controllingroll having a generally smooth nonabsorbent hard cylindrical outersurface, and said metering roll being adapted to be engaged by a movingweb at a liquid-imparting zone spaced beyond said controlling roll.

10. The metering apparatus of claim 9 wherein the outer surface of saidmetering roll comprises rubber im pregnated textile, the outer surfaceof which is defined by fibers of said textile.

11. The apparatus of claim 9 wherein said controlling roll surface isliquid adsorbent and wherein said liquid supply means comprises a meansfor applying liquid to said controlling roll surface at a point spacedfrom engagement of said controlling roll against said metering roll,whereby mutual movement of said rolls causes liquid to be carried to andflood the surface of said metering roll in a meniscus defined at the nipengagement of said rolls.

12. The apparatus of claim 9 wherein the nip between said controllingroll and said metering roll is accessible from both sides, saidapparatus being thereby adapted to receive a web threaded through saidnip to impart liquid thereto.

13. The apparatus of claim 12 wherein said liquid supply means comprisesa vat filled with liquid disposed to immerse lower portion of saidcontrolling roll, said apparatus being provided with means for traininga web through said vat to impart liquid on both sides thereto.

14. The metering apparatus of claim 9 including an adjustable impartingpressure means adapted to controllably vary the pressure of the engagedweb against said metering roll.

15. The apparatus of claim 14 wherein said adjustable imparting pressuremeans comprises a hard pressure roll mounted in a nip relation with saidmetering roll and an adustable means for controllably varying said nippressure whereby said apparatus is adapted for fine control oflow-liquid concentrations imparted to webs passing between said meteringroll and said imparting pressure roll.

16. A wide-range water metering apparatus comprising a rotatably mountedmetering roll, a rotatably mounted controllingdiooding roll disposedbelow said metering roll in a nip relation therewith accessible fromboth sides thereof, and a rotatably mounted imparting pressure rolldisposed above said metering roll in an accessible nip relationtherewith, a liquid vat disposed below said controlling-flooding rolladapted to apply liquid to the lower surfaces of saidcontrolling-flooding roll and provide clearance at the opposite sides ofsaid roll to receive a submerged web trained under saidcontrolling-flooding roll, a first and a second adjustment means adaptedto controllably vary the pressure between said controlling-flooding rolland said metering roll and between said metering roll and said impartingpressure roll respectively, said controlling-flooding roll having anadsorbent generally smooth surface, said metering roll having anadsorbent, resilient surface of no more than limited aggregativeabsorbency comprised of a large number of evenly distributed, openresiliently deformable capillaries, said pressure roll having agenerally smooth surface, said apparatus being thereby adapted to impartaccurately controlled low concentrations of liquid to said web when saidweb moves in the nip between said imparting pressure roll and saidmetering roll, and adapted to impart higher concentrations of liquidwhen the web moves in the nip between said metering roll and saidcontrolling-flooding roll, and in said vat below saidcontrolling-flooding roll.

17. A conditioning step preliminary to a physical operation on a highlyabsorbent web comprising controllably filling a multiplicity of closelydisposed uniformly distributed resilient capillaries having a pressurelimitable moisture retentive capacity in a continuous metering surfacemember by flooding said capillaries with water and then through aselectably controlled hard pressure member in pressure applying relationto said metering surface member on each side limiting the capillaryretentive capacity thereof and removing excess liquid therefrom byresilient deformation of said capillaries thereby selectively regulatingthe amount of liquid carried away and thereafter engaging said webagainst a portion of said controllably filled metering surface movingtherewith.

18. The method of claim 17 wherein said capillaries are controllablyfilled by first being flooded, and then engaged by a roll member at anip which controllably resiliently deforms the capillaries, removing acontrolled amount of liquid therefrom.

19. A method of controllably increasing the plasticity of fibers in aweb comprising flooding, with a liquid consisting essentially of water,a continuous metering surface which has an adsorbent, essentiallynonabsorbent resilient surface at which generally evenly distributedfibers define a multiplicity of evenly distributed, outwardly disposed,close together, resiliently deformable capillaries, the capillariesproviding an effective liquid retentive area such, in relation to thetotal area of the metering surface, as to provide uniform application ofliquid, pressing said flooded surface with controlled pressure in a nipdefined by hard members leaving a predetermined amount of liquid in eachof the capillaries, and directly engaging the web against said thustreated metering surface.

20. The method as claimed in claim 19 in which the web is pressed withcontrolled pressure against the metering surface by a nip defined byhard members.

References Cited in the file of this patent UNITED STATES PATENTS581,056 Bodkin Apr. 20, 1897 1,903,038 Fujii Mar. 28, 1933 2,243,604Parkinson May 27, 1941 2,531,036 Goettsch Nov. 21, 1950 2,681,636Fridolph June 22, 1954

17. A CONDITIONING STEP PRELIMINARY TO A PHYSICAL OPERATION ON A HIGHLYABSORBENT WEB COMPRISING CONTROLLABLY FILLING A MULTIPLICITY OF CLOSELYDISPOSED UNIFORMLY DIDTRIBUTED RESILIENT CAPILLARIES HAVING A PRESSURELIMITABLE MOISTURE RETENTIVE CAPACIITY IN A CONTINUOUS METERING SURFACEMEMBER BY FLOODING SAID CAPILLARIES WITH WATER AND THEN THROUGH ASELECTABLY CONTROLLED HARD PRESSURE MEMBER IN PRESSURE APPLYING RELATIONTO SAID METERING SURFACE MEMBER ON EACH SIDE LIMITING THE CAPILLARYRETENTIVE CA-